Variation of the Great Auricular Nerve and Prediction of the Facial Nerve Trunk Size

BACKGROUND: This study aimed to reveal the anatomical variation in the great auricular nerve (GAN) and the correlation between the size of the GAN and the facial nerve trunk (FNT), so as to aid surgeons to perform safe facelift surgery and parotidectomy. METHODS: Sixteen human cadavers were studied on 16 left and 15 right facial sides. The GAN’s branching patterns, location, and the mean width of the GAN and FNT were measured. RESULTS: The average distance where the nerve emerged from under the sternocleidomastoid muscle was 87.61 ± 12.13 mm when measured perpendicular to the Frankfort horizontal plane. The branching pattern of the GAN could be classified into 5 types of which the most common was type 3 (30.77%), where the GAN divided into the anterior (superficial) and posterior branches, and then the deep branch originated from the posterior branch of the GAN. The mean width of the GAN and FNT from all the dissections was 3.26 ± 0.67 mm and 3.36 ± 0.71 mm, respectively. There was a significant correlation between the width of the nerves on both facial sides (right: r =0.740, P =0.002; left: r = 0.839, P < 0.001). CONCLUSIONS: This study revealed the anatomical variation and the width of the GAN, which can strongly predict the width of the FNT. This should be taken into consideration during facelift surgery and parotidectomy, especially in patients with a small GAN to prevent iatrogenic injury to the small FNT.